Gaia was the Protogenos of earth, one of the primal elements who first emerged at the dawn of creation, along with air, sea and sky. She was the great mother of all: the heavenly gods were descended from her union with Ouranos, the sea-gods from her union with Pontos, the Gigantes from her mating with Tartaros and mortal creatures were sprung or born from her earthy flesh.

As Gaia was the source from which arose the vapours producing divine inspiration, she herself also was regarded as an oracular divinity, and it is well known that the oracle of Delphi was believed to have at first been in her possession, and at Olympia, too, she had an oracle in early times. That Ge belonged to the theoi chthinioi, requires no explanation, and hence she is frequently mentioned where they are invoked. The surnames and epithets given to Ge have more or less reference to her character as the all-producing and all-nourishing mother (mater omniparens et alma), and hence Servius classes her together with the divinities presiding over marriage. Her worship appears to have been universal among the Greeks, and she had temples or altars at Athens, Sparta, Delphi, Olympia, Bura, Tegea, Phlyus, and other places.

In myth Gaia appears as the prime opponent of the heavenly gods. First she rebelled against her husband Ouranos who had imprisoned her sons in her womb. Then later, when her son Kronos defied her by imprisoning these same sons, she assisted Zeus in his overthrow of the Titan. Finally she came into conflict with Zeus, angered with him for the binding of her Titan-sons in the pit of Tartaros. In her opposition she first produced the tribe of Gigantes and later the monster Typhoeus to dethrone him, but both failed in both attempts. In the ancient Greek cosmology earth was conceived as a flat disk encirced by the river Okeanos, and topped above by the solid dome of heaven and below by the great pit of Tartaros. She herself supported the sea and moutains upon her breast.

Gaia was depicted as a buxom, matronly woman, half risen from the earth in Greek vase painting. She was portrayed as inseperable from her native element. In mosaic art, Gaia appears as a full-figured, reclining woman, often clothed in green, and sometimes accompanied by grain spirits —the Karpoi.